Airflow diffuser for in-transit refrigeration

ABSTRACT

A diffuser apparatus for a space of a refrigeration container includes a housing having an internal chamber extending to a nozzle portion comprising a height less than a height of the internal chamber and a width greater than a width of the internal chamber, a fan disposed for operation in the internal chamber, and a heat exchanger disposed for operation in the internal chamber between the fan and the nozzle portion.

BACKGROUND

The present embodiments relate to airflow distributions for in transit refrigeration (ITR) systems.

Known apparatus and systems for airflow distribution in ITR systems are designed and constructed for optimum airflow distribution and efficiency. However, known “off the shelf” axial flow fans which are used to drive airflow through a conventional fin to a heat exchanger coil are not directed in a manner so as to maximize consistent and uniform airflow across the coil. In addition, such known systems, such as those with axial flow fans, can also contribute to the short-circuiting of the existing airflow.

It therefore would be desirable to have a diffuser and fan which are constructed to provide an even, uniform airflow velocity across 100 percent of a heat exchanger coil.

BRIEF DESCRIPTION OF THE DRAWINGS

For a more complete understanding of the present embodiments, reference may be had to the following description taken in conjunction with the drawing Figures, of which:

FIG. 1 shows a side plan view in cross-section of an embodiment of an in-transit refrigeration ITR system according to the present invention;

FIG. 2 shows a side view in cross-section of the ITR apparatus embodiment used in FIG. 2; and

FIG. 3 shows a top plan view in cross-section of the embodiment in FIG. 2.

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIG. 1, an embodiment of the in-transit refrigeration apparatus is shown generally at 10. The apparatus 10 is shown mounted in a space 12 of a container 14. The container 14 may be transported on a truck 16 or other intermodal platform such as for example a ship, barge, or railroad flatbed.

Referring also to FIGS. 2 and 3, the apparatus 10 includes a housing 18 or shroud having an internal chamber 20 or space in which a fan 22 is disposed for operation. The fan 22 is connected to and driven by a motor 24 which may be mounted to an exterior of the housing 18 as shown in FIG. 2. At least one bracket 26 or other mechanical fasteners support the housing 18 in the space 12 of the container 14. The bracket 26 may be of a type that is releasably engageable or removably mountable to the housing 18. The fan 22 may be constructed as a low profile centrifugal fan wheel.

The housing 18 is provided with an inlet 28 in communication with the space 12.

The housing 18 extends to accommodate an extension of the chamber 20 in which is disposed a heat exchanger 30. The housing 18 further extends at another side of the heat exchanger 30 as a nozzle 32 for defusing a resulting airstream which is emitted from an outlet 34 of the housing. The heat exchanger 30 is disposed for operation in the internal chamber downstream of the fan 22 and upstream of the nozzle 32. The nozzle 32 functions as a diffuser nozzle as shown in particular in FIG. 3. The nozzle 32 has a height less than a height of the internal chamber 20, and a width greater than a width of the internal chamber.

The heat exchanger 30 includes a cryogen inlet 36 and a cryogen outlet 38 in communication with the heat exchanger.

In operation, airflow 40 at the inlet 28 is drawn from the space 12 into the chamber 20 by the fan 22 and forced under pressure over a coil 31 of the heat exchanger 30. The coil 31 is constructed and arranged to fit within tight tolerances of the chamber 20 of the housing 18 so as to transfer heat from the space 12 of the container 14 over the coil 31 through which liquid cryogen passes in the heat exchanger 30. The heat exchanger 30 is also constructed and arranged so that it will diffuse the airflow 40 and thereby create a uniform airflow stream 42 which is discharged from the coil 31 and back into the space 12. When the airflow stream 42 passes out of the coil 31, it is directed by the diffuser nozzle 32 which is contoured so that a height of the diffuser nozzle is reduced and a width of the diffuser nozzle is expanded resulting in an overall cross-sectional area 44 which is constant along a substantial portion of its length. The cross-sectional area 44 of the diffuser nozzle 32 is maintained to provide a minimal pressure drop along the flow path of the airflow stream 42 so that same is distributed evenly, i.e. at a constant velocity across a width of the diffuser nozzle, and then into the space 12.

The apparatus 10 provides for the use of a single fan with a power consumption of not more than 1.0 kw. Overall heat load of the apparatus 10 is reduced and the refrigerated airflow stream 42 will be more evenly distributed throughout the space 12 of the container 14.

The present embodiments of the invention include an airflow diffuser which both creates an even velocity profile across the coil 31 of the heat exchanger 30, thereby maximizing the heat exchanger efficiency; and produces the uniform gas stream 42 having constant velocity and volumetric flow across the cross-section area 44 of the apparatus 10 as shown in FIG. 3. The uniform airflow stream 42 being discharged having a “low profile” with a constant velocity and volumetric flow is desirable for ITR systems, as such a flow provides for even distribution of container 14 refrigeration, thereby resulting in more even cooling throughout the container space 12.

The present embodiments can be retrofitted to existing shipping containers. The cryogen introduced at the cryogen inlet may be for example nitrogen or carbon dioxide.

It will be understood that the embodiments described herein are merely exemplary, and that one skilled in the art may make variations and modifications without departing from the spirit and scope of the invention. All such variations and modifications are intended to be included within the scope of the invention as described and claimed herein. Further, all embodiments disclosed are not necessarily in the alternative, as various embodiments of the invention may be combined to provide the desired result. 

What is claimed is:
 1. A diffuser apparatus for a space of a refrigeration container, comprising: a housing having an internal chamber extending to a nozzle portion comprising a height less than a height of the internal chamber and a width greater than a width of the internal chamber, a fan disposed for operation in the internal chamber, and a heat exchanger disposed for operation in the internal chamber between the fan and the nozzle portion.
 2. The diffuser apparatus of claim 1, wherein the housing further comprises an inlet at the internal chamber in fluid communication with the space of the refrigeration container, and an outlet at the nozzle portion in fluid communication with the space.
 3. The diffuser apparatus of claim 2, further comprising a cryogen inlet in communication with the heat exchanger, and a cryogen outlet in communication with the heat exchanger.
 4. The diffuser apparatus of claim 3, wherein the cryogen inlet receives a cryogenic substance selected from the group consisting of nitrogen and carbon dioxide.
 5. The diffuser apparatus of claim 1, further comprising at least one bracket disposed to mechanically fasten the housing to an interior of the refrigeration container.
 6. The diffuser apparatus of claim 5, wherein the at least one bracket is removably mountable to the housing.
 7. The diffuser apparatus of claim 1, further comprising a motor for the fan mounted to the housing external to the internal chamber.
 8. The diffuser apparatus of claim 1, wherein the heat exchanger is disposed downstream of the fan and upstream of the nozzle portion. 